I also own a different sunshield I've bought years ago and this one I bought last year is much thinner! It looks like mylar glued to a 3/4mm thin foam which my computer's TFT-display has been wrapped up with. hemmed with some other material I've also seen things packed up with, feels a little like the material froggtoggs-raingear is made of but much thinnner.
The main part is a 148cm x 68cm rectangle. There are 30cm x 24cm rounded "wings" attached to both ends (to tuck the pad between car and its doors) -- perfect for head and feet.
The pad helps to keep you warm alot and is absolutely sufficient for one who is used to sacrifices. Oh, overall weight: 74.8 g or 2.63 oz